Brominated biphenols

ABSTRACT

Bromobiphenols containing at least two bromine atoms meta to the phenolic hydroxyl groups can be produced from 3,3&#39;&#39; ,5,5&#39;&#39;-tetrasubstituted diphenoquinones by reacting the latter with bromine. The reaction can be controlled to produce little, if any, byproduct. The products obtained are dependent to some extent on the substituents in the four positions ortho to the hydroxyl groups. The biphenols can be used as antioxidants or as starting materials for preparation of flame-retardant polymeric compositions useful in the molding, coating and insulating arts.

United States Patent 1 Orlando et al.

[ Dec. 30, 1975 [54] BROMINATED BIPHENOLS [75] Inventors: Charles M.Orlando; Francois A.

A Lavallee, both of Schenectady, NY.

[73] Assignee: General Electric Company,

. Schenectady, N.Y.

22] Filed: Aug.5, 1971 [21] Appl. No.: 169,517

[52] US. Cl 260/620; 260/77.5 D; 260/348 R;

I 260/465 G; 260/469; 260/612 R; 260/869 [51] Int. Cl. C07C 39/24 [58]Field of Search 260/619 R, 620

[56] References Cited OTHER PUBLICATIONS McOmie et al., Tetrahedron,2389-2392 (1968).

J. Moir, Chem. Abstracts, Vol. 7, pp. 2380-2381 (1913).

Auwers et al., Bericlite, 38, pp. 226, 233 and 236 (1905).

Vol. 24, pp.

Moir I, S. African Jour. of Science, 8, No. 8, pp. 253-261 (1912). Moir11, S. African Jour. of Science, 9, No. 12, pp. 322-329 (1913).

Primary ExaminerPaul M. Coug'hlan, Jr.

Assistant Examiner-D. B. Springer Attorney, Agent, or FirmF. WesleyTurner; Joseph T. Cohen; Jerome C. Squillaro [57] ABSTRACT ortho to thehydroxyl groups. The biphenols can be used as antioxidants or asstarting materials for preparation of flame-retardant polymericcompositions useful in the molding, coating and insulating arts.

6 Claims, No Drawings BROMINATED BIPHENOLS no 0H BrR where R,, R R and Rare primary lower alkyl, phenyl or 4-bromophenyl and each X is hydrogenwhen R R R or R is other than primary lower alkyl and each X is brominewhen R R R and R are primary lower alkyl. These compounds are readilymade by reacting bromine with diphenoquinones having the formula,

where R R R and R are as defined above with respect to the biphenols.The numbers in the rings in the above formulae are to aid the reader inlocating the ring positions of the substituents of the compounds recitedhereinafter which are named according to accepted rules of nomenclature.

In the copending application, Ser. No. 53,648, now US. Pat. Nos3,720,721, filed July 9, 1970, and assigned to the same assignee as thepresent invention, Hans-Dieter Becker and Alfred R. Gilbert disclose thepreparation of monochlorobiphenols by reaction of hydrogen chloride withdiphenoquinones. In order to produce higher chlorinated biphenols, theinitial monochlorobiphenol must be reoxidized to thechlorodiphenoquinone and then further reacted with additional hydrogenchloride. Becker and Gilbert review the prior art methods of preparingchlorinated biphenols pointing out that mixtures of polychlorinatedproducts were obtained rather than a single product which could beeasily purified from minor impurities. No corresponding work hasapparently been done on the preparation of brominated biphenols. In viewof the desirability of preparing flame-proof plastics, it would behighly desirable to prepare starting materials such as biphenols havinga high halogen content wherein the halogen is stable under theconditions used in preparing the polymers and in fabricating theresulting polymers into which are difficult to separate and purify.Surprisingly, we have found that bromine can be used to producepolybrominated biphenols in a reaction where a single, desired productcan be produced in a high yield. This is accomplished by reacting a3,3',5,5-tetrasubstituted diphenoquinones with bromine.

If the reaction is run by adding the diphenoquinone to liquid bromine, asingle polybrominated product is obtained which is dependent on the foursubstituents on the starting diphenoquinone. When these substituents areall primary alkyl groups, the four unsubstituted diphenoquinone ringpositions are brominated yielding 2,2 ',6,6 '-tetraalkyl-3 ,3 ',5 ,5-tetrabromo-p-p'- biphenol. If the alkyl groups are secondary alkylgroups, dealkylation of some of the secondary alkyl groups occurs withbromination of the positions so vacated occurring. If tertiary alkylgroups are present, complete dealkylation occurred and some of thevacated positions are brominated. Since this dealkylation reactionintroduces bromine into the position ortho to the hydroxyl groups, it isundesirable since the bromine groups in these positions are less stablein subsequent use to form polymers and especially during molding.

.For this reason, we prefer that the alkyl groups be primary alkylgroups and still, more preferably, primary lower alkyl groups.

When the four substituents of the diphenoquinone are phenyl, only two ofthe unsubstituted diphenoquinone ring positions are brominated and thepara position of all four of the phenyl groups are brominated so thatthe product is the hexabromo compound, 3,3-dibromo-2,2',6,6'-tetra(4-bromophenyl)-p,p'- biphenol. When the foursubstituents on the diphenoquinone are both primary alkyl and phenyl,only two of the unsubstituted diphenoquinone ring positions arebrominated and the para position of the two phenyl groups arebrominated. The two diphenoquinone ring positions which are brominatedare those adjacent to the ring position occupied by the phenyl groups.For example, when the diphenoquinone is 3,3'-dimethyl-5,5'-diphenyldiphenoquionene, the product is the tetrabromobiphenol,3,3'-dibromo-2,2'-bis(4-bromophenyl)-6,6'-dimethyl-p,p"biphenol.

It will be recognized that in using liquid bromine as the reactionmedium sufficient bromine must be used to maintain a liquid phase forthe reaction. This means that more than the stoichiometric amount ofbromine is present than is required for the formation of the aboveproducts. In view of this excess bromine, it was indeed surprising tofind that only a single product from any one diphenoquinone is obtainedrather than a mixture of products and that some higher brominatedproducts were not formed, especially in the case of the phenylsubstituted diphenoquinones.

From these results, it appears that the initial bromination reactioninvolves two of the unsubstituted ring positions of the diphenoquinonewith the other two unsubstituted ring positions being unreactive towardsfurther bromination unless all four substituents of the startingdiphenoquinone are primary alkyl groups, in which case the other twounsubstituted ring positions can be brominated and the alkyl groupsremain unbrominated. When there is a phenyl substituent present,bromination proceeds until two of the unsubstituted ring positions ofthe diphenoquinone are brominated and further bromination involves onlythe para position of the phenyl substituent and then stops. This indeedis surprising in view of the excess bromine pres- 3 ent in the reaction.

Because of the high vapor pressure of bromine, and because gaseoushydrogen bromide is formed by the bromination reaction, loss of brominefrom the reaction vessel can occur if precautions, for example, use of ahighly efficient condenser, are not used. This problem is accentuated iftemperatures higher than ambient room temperature are used. Furthermore,the reaction of the diphenoquinone with bromine is an exothermicreaction. In order to maintain a liquid phase at all times, thediphenoquinone is preferably added to the liquid bromine, generally withcooling of the reaction vessel, and the rate of addition of thediphenoquinone controlled so as to not obtain an uncontrollableexotherm. The problem with volatility of the bromine and the exothermcan be alleviated by use of a nonreactive solvent, for exampleperhalogenated hydrocarbons, preferably aliphatic having a relativelylow boiling point so that they may be evaporated from the reactionmixture. A typical example is carbon tetrachloride, but other knownsolvents for halogenation reactions are well-known in the art and can beused.

When a solvent is used for the bromination reaction, the ,reaction doesnot proceed as readily to give the single brominated products mentionedabove and mixtures with lower brominated products are obtained. In orderto obtain the same products as are obtained with use of liquid bromine,heating of the reaction mixture after any exotherm has occurred willcause further bromination but the use of a Friedel-Crafts catalyst, forexample, tin or zinc halides, preferably the bromides, are veryeffective in increasing the extent of the bromination of reactions runin solution so that the results are comparable to those obtained whenliquid bromine is used. The use of the solvent can be of advantage whenlower brominated products than those mentioned above are desired, forexample, the dibrominated product where only the unsubstituted ringposition of the diphenoquinone is brominated or, in addition, whenphenyl substituents are present, some but not all of the phenylsubstituents are brominated, for example, 3,3-dibromo-2,2',6,6'-tetramethyl-p,p-biphenol, 3,3-dibromo-2,2'-bis(4-bromophenyl)-6,6'-diphenyl-p,p'- biphenol, etc. Inthis case, mixtures of brominated products will be obtained unless theusual precautions are taken, for example, use of less than astoichiometric amount of bromine required for the desired brominatedproduct, but this adversely affects the yield, addition of the bromineto the diphenoquinone dissolved in or suspended in a solvent in which itis at least partially soluble, etc.

We have found that for introduction of only two bromine groups, that thestoichiometric amount is one mole of bromine for each mole ofdiphenoquinone. Apparently, the first step in the bromination reactionis the addition of one molecule of bromine with the production of onemolecule of HBr which then in turn reacts with the intermediate productproducing the dibromo product. Subsequent bromination reactions are ofthe usual type where for each additional mole of bromine, one atom ofbromine is introduced into the product molecule and one molecule ofhydrogen bromide is evolved. We have obtained good yields of thedibrominated product when using 1.5 moles of bromine per mole ofdiphenoquinone.

One of the convenient ways of making the 3,3',5,5'- tetra-substituteddiphenoquinones starting materials is disclosed in U.S. Pat. No.3,306,875-Allan S. Hay,

4 issued Feb. 28, 1967 and assigned to the same assignee as the presentinvention. This reaction involves oxidative coupling of a2,6-disubstituted phenol using a basic cupric salt-amine complex. Inthis reaction, the two moieties of the diphenoquinone would bear thesame two substituents since two molecules of the same phenol are coupledtogether to form the diphenoquinone.

Although it would be possible to prepare diphenoquinones from a mixtureof two phenols, the reaction would not be straightforward and wouldproduce a mixture of all three possible products. Because of this, themost readily available tetra-substituted diphenoquinones are those inwhich all four substituents are identical or in which the twosubstituents on one ring are different but identical with the twodifferent substituents on the other ring, i.e. the diphenoquinones wouldhave the formula given previously where the R R R and R substituents areall identical or R and R are different and R and R are the same as R andR It is to be recognized that two different isomeric diphenoquinones arepossible, one being where R is the same as R, but different from R whichis the same as R and the other being where R is the same as R but isdifferent than R which is the same as R Such isomers are known but it isnot material to the making of our products since it is to be recognizedthat the bromination reaction converts the two isomeric diphenoquinonesinto the same brominated biphenol products.

Although we prefer to use those diphenoquinones where all foursubstituents are identical or the two substituents on the one ring aredifferent but the same as the two substituents on the other ring,because of the ease of preparation, the other 3,3',5,5-tetra-substituteddiphenoquinones can be used in our process.

Typical examples of the primary lower alkyl groups are methyl, ethyl,propyl, butyl, pentyl, hexyl, cyclohexyl, heptyl, octyl. Although otheraryl substituents other than phenyl can be substituents on thediphenoquinone, such diphenoquinones are not readily available andtherefore we prefer the aryl substituent be phenyl.

In order that those skilled in the art may better understand ourinvention, the following examples are given by way of illustration, andnot by way of limitation. In all of the examples, parts are by weightand temperatures are given in degrees Centigrade unless otherwisestated. Where elemental analyses are given, the theoretical value forthe compound is given in parentheses following the determined value.

The general procedure used with liquid bromine was to add thediphenoquinone slowly to a flask containing the liquid bromine at roomtemperature with stirring. Since an exothermic reaction occurs on theaddition of the diphenoquinone, the amount and rate of addition wascontrolled so that the temperature did not exceed 40-45 to minimize theloss of bromine in the hydrogen bromide which was evolved. When theamount of diphenoquinone was 1 to 5 g., the addition was usuallycompleted within [5 minutes. After the diphenoqui-- none addition wascompleted, the reaction mixture was stirred at room temperature so thatthe total reaction time was two hours. The residual hydrogen bromide andthe excess bromine were removed from the reaction mixture under a slowstream of nitrogen. The solid residue was then purified byrecrystallization.

EXAMPLE '1 Using the general procedure, 3.7 g.-of3,3,5,5'-tetramethyldiphenoquinone was added to 4 ml. of bromine. Therewas obtained 8.5 g., a quantitative yield of3,3,5,5-tetrabromo-2,2',6,6-tetramethyl-p,p'- biphenol having a meltingpoint of 244-246. Elemental analysis showed: C, 34.44 (34.4): H, 2.52(2.5); Br, 57.3 (57.2). The nmr spectrum showed that the methyl groupswere not brominated.

When this example was repeated on a larger scale scale using 37 g. of3,3,5,5'-tetramethyldiphenoquinone and adding it over one-half hour to120 g. of liquid bromine at room temperature, a tan colored solid wasobtained on evaporation of the excess bromine after 2 hours which aftersuspending in 200 ml. of acetone, filtered and dried gave an 86 g. yieldof the above product; nmr (8ppm., CCl,,-acetone-d 2.38 (S, 6, Aflll 7.7(S, 1, OH); mass spec. m/e: M 554-562 (quintet). k nm (e): 283 (2290),296 2500 When 1 g. of 3,3,5,5'-tetramethyldiphenoquinone' was added to 6ml. of liquid chlorine at 70 and the reaction mixture placed in an icewater bath permitting the chlorine to vaporize for a 2 hour period, awhite amorphous solid remained which could not be further purified. Asample of the chlorinated product was then reduced with zinc dust andacetic acid to give a mixture of biphenols. The major products were thenonchlorinated 2,2',6,6'-tetramethyl-p,p-biphenol, the monochlorinatedproduct 3-chloro-2,2,6,6-tetramethylp,p'-biphenol and the dichlorocompound 3,3- dichloro-2,2',6,6-tetramethyl-p,p'-biphenol.

EXAMPLE 2 Using the general procedure, 0.5 g. of3,3',5,5-tetraethyldiphenoquinone was reacted with 2 ml. of bromine togive 0.186 grams, a 20% yield of3,3',5,5-tetrabromo-2,2',6,6-tetraethyl-p,p'-biphenol having a meltingpoint at 202-204. Elemental analysis showed: C, 38.7 (39.1 H, 3.6(3.61), Br, 52.1 (52.05).1ts nmr spectrum showed no aromatic protons andthat the ethyl groups had not been brominated; nmr (8 ppm., CDCl 1.15(triplet, 6, CH QQ), 2.9 (quartet, 4, gfl CH 4.98 (S, 1, OH); mass spec.m/e: M 610-618 (quintet), h max nm (e): 283 (3040), 292 (3422).

EXAMPLE 3 Using the general procedure, 4.8 g. of3,3',5,5'-tetraphenyldiphenoquinone was added to 5 ml. of bromine. Therewas obtained a yield of 1.01 g. (13%) of 3,3-dibromo-2,2,6,6'-tetra(4-bromophenyl)-p,p'-biphenol having a meltingpoint of 265267. It was identified by its nmr and mass spectra; nmr (8ppm., C D 4.64 and 4.82 (S, 1, OH), 7.1-7.24 (m, 9, Arlj); mass spec.m/e: M 958-970 (septet).

When 3,3',5,5'-tetraisopropyldiphenoquinone was brominated according tothe general procedure, the main product isolated in a 25% yield had amelting point of l75-177. It was a partially dealkylated productcontaining 2 isopropyl groups and 4 bromine substituents, 2 of them inortho positions with respect to the hydroxyl group and 2 of them in metapositions with respect to the hydroxyl groupsi when 3,3,5,5'-tetra-t-butyldiphenoquinone was brominated according to the generalprocedure, a completely dealkylated product, melting point 216-218containing no t-butyl groups was obtained in a 98% yield. It had 5bromine groups, 3 of them in the ortho positions with respect to thehydroxyl groups and 2 of them in the meta position with respect to thehydroxyl groups. When 3,3'-di-tbutyl-5,5'-dimethyldiphenoquinone wasbrominated according to the general procedure, the main product obtainedin a 13% yield had a melting point of l93-l 95. It was completely devoidof t-butyl substituents still contained the two methyl groups andcontained 4 bromine substituents, 2 in the ortho positions and 2 in themeta positions with respect to the phenolic hydroxyl groups. The metapositions, with respect to the hydroxyl groups, which were adjacent tothe methyl groups, were not brominated.

EXAMPLE 4 A suspension of 1.0 g. of 3,3'-dimethyl-5,5'-diphenyldiphenoquinone in a solution of 0.65 g. of bromine in 5 ml. ofcarbon tetrachloride was stirred at room temperature for 40 hours. Thereaction mixture was filtered and the precipitate recrystallized from amixture of hexane and benzene to give 0.518 g. (37% yield) of3,3'-dibromo-2,2-diphenyl-6,6'-dimethyl- 1 p,p'-biphenol having amelting point of 244247. Its

elemental analysis showed: C, 59.1 (59.54), H, 3.9 (3.81); mass spec.m/e M 522-526 (triplet); nmr (5 ppm., CDCl 2.46 (doublet-J=0.6 Hz, 3,ArCH 5.40 (S, 1, -OH), 6.96 (quartet-J=0.6 Hz, 1, ArH), 7.4 (S, 5, ArH).

EXAMPLE 5 Using the general procedure, 2 g. of 3,3'-dimethyl-5,5'-diphenyldiphenoquinone was reacted with 5 ml. of bromine. Theproduct was a dark oil which was triturated with a mixture of acetoneand benzene to give a solid product which after recrystallization from ahexane-dioxane mixture gave 0.377 g. of white crystals of3,3-dibromo-2,2-bis-(4-bromophenyl)-6,6'-dimethylp,p'-biphen0l having amelting point of 324. Analysis: C, 45.9 (45.61); H, 2.8 (2.92); massspec.: m/e M 678-686 (quintet); nmr (8 ppm., d-DMF): 2.48(doublet-J=0.5Hz, 3, ArCH 7.02 (quartet-J=0.5 Hz, 1, ArH), 7.52 (A 13 pattern, 4,ArH), 7.96 (S, 1, OH).

EXAMPLE 6 This example shows the effect of solvent. To a solution of16.5 g. of bromine dissolved in 10 ml. of carbon tetrachloride, 5 g. of3,3,5,5'-tetramethyldiphenoquinone was added. After heating the reactionmixture at for 6 hours and 35 minutes, analysis by vapor phasechromatography showed that the mixture was approximately3,3',5,5'-tetrabromo-2,2',6,6'-tetramethyl-p,p-biphenol and 25%,3,3,5-tribromo-2,2',6,6'- tetramethyl-p,p'-biphenol.

EXAMPLE 7 This example illustrates the further bromination of themixtu're'of lower brominated products. When 58.6 g. of bromine was addedto a suspension of 18.5 g. of 3,3,5,5'-tetramethyldiphenoquinone in 40ml. of carbon tetrachloride at room temperature and the reaction allowedto proceed for 4 hours, there was obtained a yield of 30.1 g. of aproduct having a melting point of 227-237. Gas chromatographic analysisof the product showed that it was approximately 13% 3,3-dibromo-2,2',6,6-tetramethyl-p,p'-biphenol,' 76%3,3',S-tribromo-2,2',6,6'-tetramethyl-p,p-diphenol and l 1%3,3,5,5-tetrabromo-2,2,6,6'-tetramethyl- 7 p,p'-biphenol. A two gramsample of this mixture was added to ml. of bromine at room temperature.After 2 hours gas chromotography showed that the product was now all thetetrabromo compound.

EXAMPLE 8 This example shows the benefit to be obtained by using aFriedel-Crafts catalyst when a solvent is used. To demonstrate theeffect of the catalyst, the reaction was run both with and without thecatalyst. The general procedure used was to place 5 g. of3,3,5,5-tetramethyldiphenoquinone and 10 ml. of carbon tetrachloride ina 3-neck flask fitted with a thermometer, reflux condenser and droppingfunnel. Liquid bromine was then added to the reaction mixture and thereaction mixture heated at 70 for 4.5 hours. At the end of this time,the reaction mixture was sampled and analyzed by gas chromatography. Thecatalyst was then added and the reaction continued at room temperaturefor an additional 1.5 hours. In one case, a molar excess (overstoichiometry) of bromine was used resulting in a crude productcomposition which was 77%3,3,5,5-tetrabromo-Z,2',6,6-tetramethyl-p,p'biphenol and 23%3,3',5tribromo-Z,2',6,6-tetramethyl-p,pbiphenol. After adding 0.5 g. ofstannous chloride as a catalyst, the crude product composition wasaltered to 88% of the tetrabromobiphenol and 12% of thetribromobiphenol.

When a 65% molar excess (over stoichiometry) of bromine was used, thecrude product composition contained 73% of the tetrabromobiphenolwithout catalyst. After adding 0.5 g. of zinc bromide as catalyst, thecrude product composition was changed such that the tetrabromobiphenolcontent increased to 86% and the tribromobiphenol content decreased to14%. When repeated with zinc bromide in the initial reaction mixture,after only 2 hours at 70, the crude product composition of tetrabromocompound was 76% and tribromo compound was 24%. The results of thisexample show that the molar ratio of the bromine has little if anysignificant effect whereas the use of the Friedel-Crafts catalyst has avery significant and outstanding effect on the yield of the tetrabromoproduct.

The brominated biphenols of this invention can be used as anti-oxidantsfor petroleum products, such as gasoline, and as stabilizers againstpolymerization of monomeric materials to maintain them in theessentially unpolymerized state until such time as they are ready forpolymerization, for instance, with an organic peroxide. In addition, thehalobiphenols can be reacted with isophthaloyl or terephthaloyl halidesto make polymers in accordance with the procedures described in US. Pat.Nos. 3,036,990-992, issued May 29, 1962, and US. Pat. Nos.3,l60,602-605, issued Dec. 12, 1964, in the names of S. W. Kantor and F.F. l-lolub, all assigned to the same assignee as the present invention.The aromatic polyesters thus obtained can be used for making films andfibers, and can also be employed for making solutions of such polymersand thereafter coated on electrical conductors to form high temperatureinsulation. The presence of halogen in the dihydric biphenyl reactantimparts improved flame-resistance to such polymers. Other polyesters canbe made by reacting the halobiphenols with aliphatic dicarboxylic acids,

, or acyl halides thereof, such as adipic acid, sebacic acid, adipoylchloride, etc.

Alternatively, polycarbonate resins suitable for molding and films canbe obtained in accordance with the methods outlined in US. Pat. No.3,022,272, issued Feb. 20, 1962, and US. Pat. No. 3,018,365, issued Apr.3, 1962, by treatment of the halobiphenols with a 'phosgenating agent,e.g., diphenyl carbonate, COCl chloroformate, etc.

In addition, the brominated biphenols can be converted to esters ofmonocarboxylic acids for use as plasticizers, reacted with ethyleneoxide to form the bis(2-hydroxyethyl) ether which in turn can beincorporated into either polyesters or polycarbonates or made intoplasticizers, reacted with epichlorohydrin to form the bisglycidylethers useful in making epoxy resins, etc. For example, the followingderivatives have been prepared by reaction of 3,3',5,5'-tetrabromo-2,2,6,6-tetramethy1-p,p-biphenol with the following reagents: (1Ethylene chlorohydrin was reacted in the presence of a water-ethanolsolution of sodium hydroxide to prepare the mono(2-hydroxyethyl) etherand the bis(2-hydroxyethyl) ether, depending on the molar ratio of thetwo reactants. The bis(2-hydroxyethyl) ether was further reacted withadditional ethylene chlorohydrin to convert one of the 2-hydroxyethylether groups to a 2-(2-hydroxyethoxy) ethyl ether group. (2) Afterreacting the biphenol with sodium methylate to prepare the di-sodiumsalt, the latter was reacted as the dry salt with a-epichlorohydrin toprepare the diglycidyl ether. (3) A mixture of acetic acid and aceticanhydride to prepare the diacetate ester. (4) Allyl chloride to preparethe diallyl ether. (5) Cyanogen bromide to replace both hydroxy groupswith CN groups. The products of reactions 1, 2, 4 and 5, like thebromobiphenols of this invention have been converted to variouspolymers.

For example, the products of reactions 4 and 5 are polymerizable whenheated with or without a polymerization catalyst. They can bepolymerized alone or with other polymerizable monomers. The products ofreaction 3 are converted to epoxy resins, either alone or with otherepoxides, by reaction with monomeric or polymeric diols in the presenceof polyamine or anhydride catalysts. The products of reaction 1 can bereacted to form polyesters with dicarboxylic acids by ester interchangewith low molecular weight glycols, e.g., 1,4-butanediol, etc.,polyesters of terephthalic acid in the presence of a transesterificationcatalyst to produce homopolyesters as well as copolyesters. Thesepolyesters, like the other polymers described above have flame-resistantproperties per se, or can be blended with other polymers to impartflame-resistant properties to the blends. Other additives known toincrease the flame-resistance of halogen containing polymers, forexample, antimony oxide can also be added to further increase theflame-resistant properties.

Obviously, other modifications or variations of the present inventionare possible in light of the above teachings and disclosures. [t is,therefore, to be understood that changes may be made in the particularembodiments of the invention described which are within the fullintended scope invention as defined by the appended claims.

What 1 claim as. new and desire to secure by Letters Patent of the U.Sis:

1. A chemical compound of the formula 2. The compound of claim 1, whereeach R R R and R is a methyl radical.

3. The compound of claim 1, where each R R R and R is an ethyl radical.

4. The compound of claim 1, where each R and R is a methyl radical andeach R and R is an ethyl radical. Br 5. The compound of claim 1, whereeach R and R is a methyl radical and each R and R is an ethyl radical.

6. The compound of claim 1, where each R R and R is a methyl radical andR is an ethyl radical.

where independently each R R R and R is a normal methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl or octyl.

1. A CHEMICAL COMPOUND OF THE FORMULA
 2. The compound of claim 1, whereeach R1, R2, R3 and R4 is a methyl radical.
 3. The compound of claim 1,where each R1, R2, R3 and R4 is an ethyl radical.
 4. The compound ofclaim 1, where each R1 and R2 is a methyl radical and each R3 and R4 isan ethyl radical.
 5. The compound of claim 1, where each R1 and R3 is amethyl radical and each R2 and R4 is an ethyl radical.
 6. The compoundof claim 1, where each R1, R2 and R3 is a methyl radical and R4 is anethyl radical.